Add support for enabling Secure AVIC VMSA SEV feature in SEV-SNP guests
through a new "secure-avic" boolean property on SEV-SNP guest objects.

Sample command-line:
  -machine q35,confidential-guest-support=sev0 \
  -object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1,secure-avic=on

Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
---
 target/i386/sev.h |  1 +
 target/i386/sev.c | 13 +++++++++++++
 qapi/qom.json     |  5 ++++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/target/i386/sev.h b/target/i386/sev.h
index 87e73034ad15..a374c144bccd 100644
--- a/target/i386/sev.h
+++ b/target/i386/sev.h
@@ -47,6 +47,7 @@ bool sev_snp_enabled(void);
 #define SVM_SEV_FEAT_SNP_ACTIVE     BIT(0)
 #define SVM_SEV_FEAT_DEBUG_SWAP     BIT(5)
 #define SVM_SEV_FEAT_SECURE_TSC     BIT(9)
+#define SVM_SEV_FEAT_SECURE_AVIC    BIT(16)
 
 typedef struct SevKernelLoaderContext {
     char *setup_data;
diff --git a/target/i386/sev.c b/target/i386/sev.c
index facf51c810d9..f9170e21ca57 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -3147,6 +3147,16 @@ static void sev_snp_guest_set_secure_tsc(Object *obj, bool value, Error **errp)
     sev_set_feature(SEV_COMMON(obj), SVM_SEV_FEAT_SECURE_TSC, value);
 }
 
+static bool sev_snp_guest_get_secure_avic(Object *obj, Error **errp)
+{
+    return is_sev_feature_set(SEV_COMMON(obj), SVM_SEV_FEAT_SECURE_AVIC);
+}
+
+static void sev_snp_guest_set_secure_avic(Object *obj, bool value, Error **errp)
+{
+    sev_set_feature(SEV_COMMON(obj), SVM_SEV_FEAT_SECURE_AVIC, value);
+}
+
 static void
 sev_snp_guest_get_tsc_frequency(Object *obj, Visitor *v, const char *name,
                                 void *opaque, Error **errp)
@@ -3210,6 +3220,9 @@ sev_snp_guest_class_init(ObjectClass *oc, const void *data)
     object_class_property_add(oc, "tsc-frequency", "uint32",
                               sev_snp_guest_get_tsc_frequency,
                               sev_snp_guest_set_tsc_frequency, NULL, NULL);
+    object_class_property_add_bool(oc, "secure-avic",
+                                  sev_snp_guest_get_secure_avic,
+                                  sev_snp_guest_set_secure_avic);
 }
 
 static void
diff --git a/qapi/qom.json b/qapi/qom.json
index 5b99148cb790..5dce560a2f54 100644
--- a/qapi/qom.json
+++ b/qapi/qom.json
@@ -1105,6 +1105,8 @@
 # @tsc-frequency: set secure TSC frequency. Only valid if Secure TSC
 #     is enabled (default: zero) (since 10.2)
 #
+# @secure-avic: enable Secure AVIC (default: false) (since 10.2)
+#
 # Since: 9.1
 ##
 { 'struct': 'SevSnpGuestProperties',
@@ -1118,7 +1120,8 @@
             '*host-data': 'str',
             '*vcek-disabled': 'bool',
             '*secure-tsc': 'bool',
-            '*tsc-frequency': 'uint32' } }
+            '*tsc-frequency': 'uint32',
+            '*secure-avic': 'bool' } }
 
 ##
 # @TdxGuestProperties:
-- 
2.50.1